1. Field of the Invention
The invention is based on a brake system for vehicles, in particular to an improved brake system for motor vehicles.
2. Description of the Prior Art
In a known brake system of this type (German Patent Disclosure DE 195 21 832 A1), the pressure measuring elements are combined in a sensor plate, which is screwed to the hydraulic block by means of screws passed through screw holes in the sensor plate. The measuring diaphragms of the individual pressure measuring elements, which in conjunction with the gauge form the pressure measuring element, are each acted upon by fluid via a respective fluid conduit. For sealing purposes, a sealing plate is placed between the sensor plate and the hydraulic block. The strain gauges are disposed on the surface of the measuring diaphragm and are electrically conductively connected to an evaluation circuit. The evaluation circuit is mounted on a flat double-T-shaped carrier, which is screwed to the hydraulic block, extending a slight distance above the sensor plate. The evaluation circuit can evaluate the resistances of the strain gauges of all the pressure measuring elements separately, for instance by multiplexing. The evaluation circuit is connected to the control unit via the cable harness of the electrical system.
The brake system of the invention has the advantage that by integrating the pressure sensor and the control unit, only a single housing is needed, and the electrical connection between the pressure sensor and the control unit can be made over the shortest distance and in a protected way inside the housing. The electrical connection among pressure measuring elements, signal processing and the control unit computer can be done on one level by bonded connections and hybrid technology, thus achieving greater security against failure and requiring fewer components. Installation is simple, because the housing is merely joined to the hydraulic block, that is, put in place and secured. The complicated installation step of connecting the individual pressure connections of the pressure sensor to the hydraulic block that is otherwise customary is omitted, since this is achieved automatically and very simply in the joining operation. By means of the small-diameter plug-in tubes of the pressure measuring elements, the pressure measurement takes place in a straight conduit, and because of the small tube diameter, only turbulence arises in the conduit through which fluid flows, thus considerably increasing the accuracy of detection of the controlled brake pressure. The long plug-in tubes also assure compensation for tolerances transversely to the longitudinal direction of the plug-in tubes when the housing and the hydraulic block are joined to one another.
In a preferred embodiment of the invention, the pressure measuring elements are disposed side by side on a carrier and are inserted, each with a collar coaxially surrounding the plug-in tube, into stepped bores embodied in the carrier. By means of wedging segments protruding radially from the underside of the collar, the pressure measuring elements are wedged into the carrier on its underside. By these structural provisions, simple fastening of the pressure measuring elements by wedging is possible. The collar fixes each of the pressure measuring elements in their position, so as to achieve the requisite angular precision. The undercut on the lower end of the collar prevents the forces arising from the wedging from reaching the region of the pressure measuring cell and adulterating the measurement signal.
In an advantageous embodiment of the invention, the sealing off of the plug-in tubes, protruding into the fluid conduits of the hydraulic block, of the pressure measuring elements is done in each case by means of two O-rings, slipped onto the plug-in tube and which O-rings are disposed on both sides of a support disk coaxially surround the plug-in tube. This double-O-ring seal not only serves to seal off the fluid conduits but also makes it possible to compensate for tolerances in the axial direction between the housing and the hydraulic block when these two components are joined.
In an advantageous embodiment of the invention, radial bores discharging into the fluid conduits are made in the hydraulic block, and the ends of the plug-in tubes of the pressure measuring elements are passed through these bores. One trap funnel is inserted into each of the openings of the radial bores at the surface of the hydraulic block. This trap funnel makes it easier to insert the respective plug-in tube into the fluid conduits positionally correctly and at the same time serves to hold down the double-O ring seal.